insidious

adjective

Definition of insidiousnext
as in treacherous
formal causing harm in a way that is gradual or not easily noticed Most people with this insidious disease have no idea that they are infected. an insidious enemy

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Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of insidious But, as Ellis demonstrates in this survey of the city’s racial history, liberal policy achievements tend to obscure more insidious forms of exclusion. — The New Yorker, New Yorker, 20 July 2026 Beneath all the splendor, the couture, the balls, and the opera lurked an undercurrent of hatred, one that would fester and erupt in ways both insidious and catastrophic. — Literary Hub, 17 July 2026 But this last year, in particular, has broken new, insidious ground. — Los Angeles Times, 16 July 2026 In my view, statements to that effect are shortsighted, prioritizing short-term social effects over more insidious and long-term issues, including addiction. — Emma Fenske, The Conversation, 2 July 2026 See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
  1. treacherous
  2. subtle
  3. false
  4. deceptive
  5. perfidious
  6. incorrect
  7. wrong
Adjective
  • While the unanimous support from FDA advisors boded well for Moderna’s shot, the overall path to approval was treacherous and uncertain, even until the end.
    — Beth Mole, ArsTechnica, 6 Aug. 2026
  • Fleeing an economic crisis and political repression back home, many Venezuelans have risked their lives on treacherous journeys to reach the US.
    — Rocio Munoz, CNN Money, 4 Aug. 2026
Definition of treacherous
Adjective
  • The herbal shiso adds a subtle savory depth, delivering a clean, refreshing balance to the textures and flavor.
    — Angela Hansberger, AJC.com, 7 Aug. 2026
  • Ask someone to review a two-hour video and identify subtle violations, and they are almost guaranteed to miss something.
    — Tal Lev-Ami, Forbes.com, 7 Aug. 2026
Definition of subtle
Adjective
  • There are factors that could tilt in favor of Fauci’s strategy, including the fact that his pardon would not protect him from potential state prosecutions or from a federal prosecution related to any testimony that investigators deemed false.
    — Eric Tucker, Chicago Tribune, 5 Aug. 2026
  • Yet, the suit added, county officials later acknowledged that was false; no one from DCFS saw Sophia in person after that September 2021 report.
    — Jakob Rodgers, Mercury News, 5 Aug. 2026
Definition of false
Adjective
  • The county attorney presented a plan to sue several big pharma companies for the deceptive marketing practices that triggered the opioid epidemic, following the pattern established by lawsuits filed against tobacco companies starting in the 1990s.
    — Guthrie Scrimgeour, Rolling Stone, 2 Aug. 2026
  • Outside companies can test systems for cybersecurity risks, deceptive behavior, privacy failures, bias and dangerous capabilities.
    — Gerui Wang, Forbes.com, 1 Aug. 2026
Definition of deceptive
Adjective
  • Logan Marshall-Green as Melanthius Melanthius is a perfidious goatherd who sides with Antinous.
    — Hannah Abraham, Forbes.com, 18 July 2026
  • This is perhaps the most perfidious practice of this sort of politics.
    — David M. Drucker, Twin Cities, 3 June 2026
Definition of perfidious
Adjective
  • Artificial intelligence can worsen this by confidently directing attention, causing users to stop searching prematurely if AI's initial answer is plausible but incorrect.
    — Dr. Diane Hamilton, Forbes.com, 3 Aug. 2026
  • Incorrect Brew Temperature or Pressure While rather technical, Mynatt notes that using incorrect brew temperatures or pressures can have a significant impact on your espresso and latte.
    — Better Homes & Gardens, Better Homes & Gardens, 2 Aug. 2026
Definition of incorrect
Adjective
  • The agent that flagged a bad clause in June stops flagging it in July, and nobody did anything wrong, and nothing broke.
    — Jason Snyder, Forbes.com, 8 Aug. 2026
  • Using the wrong type of cleaning product for your tub’s material can result in scratches, discoloration, or chips.
    — Ashlyn Needham, Southern Living, 8 Aug. 2026
Definition of wrong

Browse Nearby Words

inside tracks
insidious
insidiously
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Cite this Entry

“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 10 Aug. 2026.

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